1. Field of the Invention
The present invention relates to a substrate holding apparatus, a mask alignment method, and a vacuum processing system. In particular, the present invention relates to a substrate holding apparatus and a mask alignment method for positioning a mask with respect to a substrate with high accuracy and excellent reproducibility, while reducing the occurrence of particles, and also relates to a vacuum processing apparatus comprising the substrate holding apparatus.
2. Description of the Related Art
In film deposition apparatuses such as sputtering apparatus and chemical vapor deposition (CVD) apparatuses, a film deposition process is performed with a substrate held on a substrate holder. In this process, it is often difficult to control film qualities, such as film thickness, since an outer circumferential edge (substrate outer edge) of the substrate is chamfered. In particular, in a case when a deposition material, which is prone to exfoliating, is deposited, the deposited material adhering to the outer edge of the substrate may exfoliate to produce particles.
To avoid deposition on the substrate outer edge, a deposition process is performed with the target side of the substrate outer edge covered with a ring-shaped mask, in some cases. (See Japanese Patent Application Publication No. 2001-274104.) Although the mask can prevent deposition on the substrate outer edge, an effective film area may be reduced in a case when the mask is misaligned with respect to the substrate. In other words, a region on the substrate in which deposition is normally performed may vary, and this variation may reduce the number of producible chips. Accordingly, in the case when the mask is used, it is desirable to provide a positioning mechanism for controlling the position of the mask with respect to the substrate with high reproducibility.
As a configuration example of a mechanism for positioning between the substrate (substrate stage) and the mask, a mask positioning mechanism (centering mechanism) will be described, which is shown in FIGS. 7 to 10 of Japanese Patent Application Publication No. 2001-274104. The mechanism described in Japanese Patent Application Publication No. 2001-274104 is provided in a structure in which the substrate stage and the mask are separated in the process of setting the substrate, and has a centering function by engaging conical taper pins formed on the mask side with conical grooves formed on the substrate stage side.
In the technique described in Japanese Patent Application Publication No. 20010274104, however, the gaps between the taper pins and the holes need to be large, in order to prevent galling between the conical taper pins and the holes. Accordingly, the above-described mechanism has a problem of not being necessarily suitable as a mechanism for performing positioning with high accuracy.
On the other hand, in addition to effective film area improvement and mask positioning accuracy improvement, further particle reduction and maintenance cost reduction are desired, from the viewpoints of electronic device density growth and productivity improvement.